The electrical systems commonly used on recreational vehicles, such as snowmobiles, all-terrain vehicles or small personal watercraft, typically contains an engine-driven alternator usually of a permanent magnet type. This alternator supplies power to the vehicle's electrical system which may consist of a battery, used for starting or other loads, and a lighting system. The lighting system may be run either directly from the alternating current output of the alternator or from the battery. In watercrafts, fuel pumps and bilge pumps are commonly part of the electrical load. A manual switch is sometimes used to turn off and on lights partially when the lights are run from the battery. Safety considerations, and in some cases government regulations, may prescribe that lights on recreational vehicles be on all the time that the engine is operating. The batteries on these vehicles are relatively small and the alternator outputs are frequently insufficient to supply the full brilliance of the lights at engine idle. Therefore, batteries are frequently run down either by operation with extended periods at idle or by the light not being turned off promptly when the engine is stopped. It is the purpose of this invention to supply an automated system for controlling lights or other loads. This system is responsive to the operation of the engine to turn on the load whenever the engine is operating, or only above a selected engine speed. One version of this invention is also responsive to the state of charge of the vehicle battery, automatically reducing the power to the lights to the power available from the alternator when the battery is below a given voltage. It is an object of this invention to utilize the alternator power to operate loads as required without manual load switching by the vehicle operator.